The present invention relates to a novel cytokine expressed by neutrophils which has therefore been designated Neutrokine-xcex1 protein (xe2x80x9cNeutrokine-xcex1xe2x80x9d). In particular, isolated nucleic acid molecules are provided encoding the Neutrokine-xcex1 protein. Neutrokine-xcex1 polypeptides are also provided, as are vectors, host cells and recombinant methods for producing the same.
Human tumor necrosis factors (TNF-xcex1) and (TNF-xcex2, or lymphotoxin) are related members of a broad class of polypeptide mediators, which includes the interferons, interleukins and growth factors, collectively called cytokines (Beutler, B. and Cerami, A., Annu. Ret,. Immunol., 7:625-655 (1989)). Sequence analysis of cytokine receptors has defined several subfamilies of membrane proteins (1) the Ig superfamily, (2) the hematopoietin (cytokine receptor superfamily and (3) the tumor necrosis factor (TNF)/nerve growth factor (NGF) receptor superfamily (for review of TNF superfamily see, Gruss and Dower, Blood 85(12):3378-3404 (1995) and Aggarwal and Natarajan, Eur. Cytokine Netw., 7(2):93-124 (1996)). The TNF/NGF receptor superfamily contains at least 10 difference proteins. Gruss and Dower, supra. Ligands for these receptors have been identified and belong to at least two cytokine superfamilies. Gruss and Dower, supra.
Tumor necrosis factor (a mixture of TNF-xcex1 and TNF-xcex2) was originally discovered as a result of its anti-tumor activity, however, now it is recognized as a pleiotropic cytokine capable of numerous biological activities including apoptosis of some transformed cell lines, mediation of cell activation and proliferation and also as playing important roles in immune regulation and inflammation.
To date, known members of the TNF-ligand superfamily include TNF-xcex1, TNF-xcex2 (lymphotoxin-xcex1), LT-xcex2, OX40L, Fas ligand, CD30L, CD27L, CD40L and 4-IBBL. The ligands of the TNF ligand superfamily are acidic, TNF-like molecules with approximately 20% sequence homology in the extracellular domains (range, 12%-36%) and exist mainly as membrane-bound forms with the biologically active form being a trimeric/multimeric complex. Soluble forms of the TNF ligand superfamily have only been identified so far for TNF, LT-xcex2, and Fas ligand (for a general review, see Gruss, H. and Dower, S. K., Blood, 85(12):3378-3404 (1995)), which is hereby incorporated by reference in its entirety. These proteins are involved in regulation of cell proliferation, activation, and differentiation, including control of cell survival or death by apoptosis or cytotoxicity (Armitage, R. J., Curr. Opin. Immunol. 6:407 (1994) and Smith, C. A., Cell 75:959 (1994)).
Tumor necrosis factor-alpha (TNF-xcex1; also termed cachectin; hereinafter xe2x80x9cTNFxe2x80x9d) is secreted primarily by monocytes and macrophages in response to endotoxin or other stimuli as a soluble homotrimer of 17 kD protein subunits (Smith, R. A. et al., J. Biol. Chem. 262:6951-6954 (1987)). A membrane-bound 26 kD precursor form of TNF has also been described (Kriegler, M. et al., Cell 53:45-53 (1988)).
Accumulating evidence indicates that TNF is a regulatory cytokine with pleiotropic biological activities. These activities include: inhibition of lipoprotein lipase synthesis (xe2x80x9ccachectinxe2x80x9d activity) (Beutler, B. et al., Nature 316:552 (1985)), activation of polymorphonuclear leukocytes (Klebanoff, S. J. et al., J. Immunol. 136:4220 (1986); Perussia, B., et al., J. Immunol. 138:765 (1987)), inhibition of cell growth or stimulation of cell growth (Vilcek, J. et al., J. Exp. Med. 163:632 (1986); Sugarman, B. J. et al., Science 230:943 (1985); Lachman, L. B. et al., J. Immunol. 138:2913 (1987)), cytotoxic action on certain transformed cell types (Lachman, L. B. et al., supra; Darzynkiewicz, Z. et al., Canc. Res. 44:83 (1984)), antiviral activity (Kohase, M. et al., Cell 45:659 (1986); Wong, G. H. W. et al., Nature 323:819 (1986)), stimulation of bone resorption (Bertolini, D. R. et al., Nature 319:516 (1986); Saklatvala, J., Nature 322:547 (1986)), stimulation of collagenase and prostaglandin E2 production (Dayer, J.-M. et al., J. Exp. Med. 162:2163 (1985)); and immunoregulatory actions, including activation of T cells (Yokota, S. et al., J. Immunol. 140:531 (1988)), B cells (Kehrl, J. H. et al., J. Exp. Med. 166:786 (1987)), monocytes (Philip, R. et al, Nature 323:86 (1986)), thymocytes (Ranges, G. E. et al., J. Exp. Med. 167:1472 (1988)), and stimulation of the cell-surface expression of major histocompatibility complex (MHC) class I and class II molecules (Collins, T. et al., Proc. Natl. Acad. Sci. USA 83:446 (1986); Pujol-Borrel, R. et al., Nature 326:304 (1987)).
TNF is noted for its pro-inflammatory actions which result in tissue injury, such as induction of procoagulant activity on vascular endothelial cells (Pober, J. S. et al., J. Immunol. 136:1680 (1986)), increased adherence of neutrophils and lymphocytes (Pober, J. S. et al., J. Immunol. 138:3319 (1987)), and stimulation of the release of platelet activating factor from macrophages, neutrophils and vascular endothelial cells (Camussi, G. et al., J. Exp. Med. 166:1390 (1987)).
Recent evidence implicates TNF in the pathogenesis of many infections (Cerami, A. et al., Immunol. Today 9:28 (1988)), immune disorders, neoplastic pathology, e.g., in cachexia accompanying some malignancies (Oliff, A. et al., Cell 50:555 (1987)), and in autoimmune pathologies and graft-versus host pathology (Piguet, P.-F. et al., J. Exp. Med. 166:1280 (1987)). The association of TNF with cancer and infectious pathologies is often related to the host""s catabolic state. A major problem in cancer patients is weight loss, usually associated with anorexia. The extensive wasting which results is known as xe2x80x9ccachexiaxe2x80x9d (Kern, K. A. et al. J. Parent. Enter. Nutr. 12:286-298 (1988)). Cachexia includes progressive weight loss, anorexia, and persistent erosion of body mass in response to a malignant growth. The cachectic state is thus associated with significant morbidity and is responsible for the majority of cancer mortality. A number of studies have suggested that TNF is an important mediator of the cachexia in cancer, infectious pathology, and in other catabolic states.
TNF is thought to play a central role in the pathophysiological consequences of Gram-negative sepsis and endotoxic shock (Michie, H. R. et al., Br. J. Surg. 76:670-671 (1989); Debets, J. M. H. et al., Second Vienna Shock Forum, p.463-466 (1989); Simpson, S. Q. et al, Crit. Care Clin. 5:27-47 (1989)), including fever, malaise, anorexia, and cachexia. Endotoxin is a potent monocyte/macrophage activator which stimulates production and secretion of TNF (Kornbluth, S. K. et al., J. Immunol. 137:2585-2591 (1986)) and other cytokines. Because TNF could mimic many biological effects of endotoxin, it was concluded to be a central mediator responsible for the clinical manifestations of endotoxin-related illness. TNF and other monocyte-derived cytokines mediate the metabolic and neurohormonal responses to endotoxin (Michie, H. R. et al., N. Eng. J. Med. 318:1481-1486 (1988)). Endotoxin administration to human volunteers produces acute illness with flu-like symptoms including fever, tachycardia, increased metabolic rate and stress hormone release (Revhaug, A. et al., Arch. Surg. 123:162-170 (1988)). Elevated levels of circulating TNF have also been found in patients suffering from Gram-negative sepsis (Waage, A. et al., Lancet 1:355-357 (1987); Hammerle, A. F. et al., Second Vienna Shock Forum p. 715-718 (1989); Debets, J. M. H. et al., Crit. Care Med. 17:489-497 (1989); Calandra, T. et al, J. Infec. Dis. 161:982-987 (1990)).
Passive immunotherapy directed at neutralizing TNF may have a beneficial effect in Gram-negative sepsis and endotoxemia, based on the increased TNF production and elevated TNF levels in these pathology states, as discussed above. Antibodies to a xe2x80x9cmodulatorxe2x80x9d material which was characterized as cachectin (later found to be identical to TNF) were disclosed by Cerami et al. (EPO Patent Publication 0,212,489, Mar. 4, 1987). Such antibodies were said to be useful in diagnostic immunoassays and in therapy of shock in bacterial infections. Rubin et al. (EPO Patent Publication 0,218,868, Apr. 22, 1987) disclosed monoclonal antibodies to human TNF, the hybridomas secreting such antibodies, methods of producing such antibodies, and the use of such antibodies in immunoassay of TNF. Yone et al. (EPO Patent Publication 0,288,088, Oct. 26, 1988) disclosed anti-TNF antibodies, including mAbs, and their utility in immunoassay diagnosis of pathologies, in particular Kawasaki""s pathology and bacterial infection. The body fluids of patients with Kawasaki""s pathology (infantile acute febrile mucocutaneous lymph node syndrome; Kawasaki, T., Allergy 16:178 (1967); Kawasaki, T., Shonica (Pediatrics) 26:935 (1985)) were said to contain elevated TNF levels which were related to progress of the pathology (Yone et al., supra).
Other investigators have described mAbs specific for recombinant human TNF which had neutralizing activity in vitro (Liang, C-M. et al. Biochem. Biophys. Res. Comm. 137:847-854 (1986); Meager, A. et al., Hybridoma 6:305-311 (1987); Fendly et al., Hybridoma 6:359-369 (1987); Bringman, T S et al., Hybridoma 6:489-507 (1987); Hirai, M. et al., J. Immunol. Meth. 96:57-62 (1987); Moller, A. et al. (Cytokine 2:162-169 (1990)). Some of these mAbs were used to map epitopes of human TNF and develop enzyme immunoassays (Fendly et al., supra; Hirai et al., supra; Moller et al., supra) and to assist in the purification of recombinant TNF (Bringman et al., supra). However, these studies do not provide a basis for producing TNF neutralizing antibodies that can be used for in vivo diagnostic or therapeutic uses in humans, due to immunogenicity, lack of specificity and/or pharmaceutical suitability.
Neutralizing antisera or mAbs to TNF have been shown in mammals other than man to abrogate adverse physiological changes and prevent death after lethal challenge in experimental endotoxemia and bacteremia. This effect has been demonstrated, e.g., in rodent lethality assays and in primate pathology model systems (Mathison, J. C. et al., J. Clin. Invest. 81:1925-1937 (1988); Beutler, B. et al., Science 229:869-871 (1985); Tracey, K. J. et al., Nature 330:662-664 (1987); Shimamoto, Y. et al, Immunol. Lett. 17:311-318 (1988); Silva, A. T. et al., J. Infect. Dis. 162:421-427 (1990); Opal, S. M. et al., J. Infect. Dis. 161:1148-1152 (1990); Hinshaw, L. B. et al., Circ. Shock 30:279-292 (1990)).
To date, experience with anti-TNF mAb therapy in humans has been limited but shows beneficial therapeutic results, e.g., in arthritis and sepsis. See, e.g., Elliott, M. J. et al., Baillieres Clin. Rheumatol. 9:633-52 (1995); Feldmann M, et al., Ann. N.Y. Acad. Sci. USA 766:272-8 (1995); van der Poll, T. et al., Shock 3:1-12 (1995); Wherry et al., Crit. Care. Med. 21:S436-40 (1993); Tracey K. J., et al., Crit. Care Med. 21:S415-22 (1993).
Mammalian development is dependent on both the proliferation and differentiation of cells as well as programmed cell death which occurs through apoptosis (Walker, et al., Methods Achiev. Exp. Pathol. 13:18 (1988). Apoptosis plays a critical role in the destruction of immune thymocytes that recognize self antigens. Failure of this normal elimination process may play a role in autoimmune diseases (Gammon et al., Immunology Today 12:193 (1991)).
Itoh et al. (Cell 66:233 (1991)) described a cell surface antigen, Fas/CD23 that mediates apoptosis and is involved in clonal deletion of T-cells. Fas is expressed in activated T-cells, B-cells, neutrophils and in thymus, liver, heart and lung and ovary in adult mice (Watanabe-Fukunaga et al., J. Immunol. 148:1274 (1992)) in addition to activated T-cells, B-cells, neutorophils. In experiments where a monoclonal Ab is cross-linked to Fas, apoptosis is induced (Yonehara et al., J. Exp. Med. 169:1747 (1989); Trauth et al., Science 245:301 (1989)). In addition, there is an example where binding of a monoclonal Ab to Fas is stimulatory to T-cells under certain conditions (Alderson et al., J. Exp. Med. 178:2231 (1993)).
Fas antigen is a cell surface protein of relative MW of 45 Kd. Both human and murine genes for Fas have been cloned by Watanabe-Fukunaga et al., (J. Immunol. 148:1274 (1992)) and Itoh et al. (Cell 66:233 (1991)). The proteins encoded by these genes are both transmembrane proteins with structural homology to the Nerve Growth Factor/Tumor Necrosis Factor receptor superfamily, which includes two TNF receptors, the low affinity Nerve Growth Factor receptor and CD40, CD27, CD30, and OX40.
Recently the Fas ligand has been described (Suda et al., Cell 75:1169 (1993)). The amino acid sequence indicates that Fas ligand is a type II transmembrane protein belonging to the TNF family. Thus, the Fas ligand polypeptide comprises three main domains: a short intracellular domain at the amino terminal end and a longer extracellular domain at the carboxy terminal end, connected by a hydrophobic transmembrane domain. Fas ligand is expressed in splenocytes and thymocytes, consistent with T-cell mediated cytotoxicity. The purified Fas ligand has a MW of 40 kD.
Recently, it has been demonstrated that Fas/Fas ligand interactions are required for apoptosis following the activation of T-cells (Ju et al., Nature 373:444 (1995); Brunner et al., Nature 3 73:441 (1995)). Activation of T-cells induces both proteins on the cell surface. Subsequent interaction between the ligand and receptor results in apoptosis of the cells. This supports the possible regulatory role for apoptosis induced by Fas/Fas ligand interaction during normal immune responses.
Accordingly, there is a need to provide cytokines similar to TNF that are involved in pathological conditions. Such novel cytokines could be used to make novel antibodies or other antagonists that bind these TNF-like cytokines for therapy of disorders related to TNF-like cytokines.
The present invention provides isolated nucleic acid molecules comprising a polynucleotide encoding a cytokine that is structurally similar to TNF and related cytokines and is believed to have similar biological effects and activities. This cytokine is named Neutrokine-xcex1 and the invention includes Neutrokine-xcex1 polypeptides having at least a portion of the amino acid sequence in FIGS. 1A and 1B (SEQ ID NO:2) or amino acid sequence encoded by the cDNA clone deposited in a bacterial host on Oct. 22, 1996 assigned ATCC number 97768. The nucleotide sequence determined by sequencing the deposited Neutrokine-xcex1 clone, which is shown in FIGS. 1A and 1B (SEQ ID NO:1), contains an open reading frame encoding a complete polypeptide of 285 amino acid residues including an N-terminal methionine, a predicted intracellular domain of about 46 amino acid residues, a predicted transmembrane domain of about 26 amino acids, a predicted extracellular domain of about 213 amino acids, and a deduced molecular weight for the complete protein of about 31 kDa. As for other type II transmembrane proteins, soluble forms of Neutrokine-xcex1 include all or a portion of the extracellular domain cleaved from the transmembrane domain and a polypeptide comprising the complete Neutrokine-xcex1 polypeptide lacking the transmembrane domain, i.e., the extracellular domain linked to the intracellular domain.
Thus, one aspect of the invention provides an isolated nucleic acid molecule comprising a polynucleotide having a nucleotide sequence selected from the group consisting of: (a) a nucleotide sequence encoding a full-length Neutrokine-xcex1 polypeptide having the complete amino acid sequence in FIGS. 1A and 1B (SEQ ID NO:2) or as encoded by the cDNA clone contained in the ATCC Deposit of Oct. 22, 1996 ATCC Number 97768; (b) a nucleotide sequence encoding the predicted extracellular domain of the Neutrokine-xcex1 polypeptide having the amino acid sequence at positions 73 to 285 in FIGS. 1A and 1B (SEQ ID NO:2) or as encoded by the cDNA clone contained in ATCC No. 97768 deposited on Oct. 22, 1996; (c) a nucleotide sequence encoding a polypeptide comprising the Neutrokine-xcex1 intracellular domain (amino acid residues from about 1 to about 46 in FIGS. 1A and 1B (SEQ ID NO:2)) or as encoded by the cDNA clone contained in ATCC No. 97768 deposited on Oct. 22, 1996; (d) a nucleotide sequence encoding a polypeptide comprising the Neutrokine-xcex1 transmembrane domain (amino acid residues from about 47 to about 72 in FIGS. 1A and 1B (SEQ ID NO:2) or as encoded by the cDNA clone contained in ATCC No. 97768 deposited on Oct. 22, 1996; (e) a nucleotide sequence encoding a soluble Neutrokine a polypeptide having the extracellular and intracellular domains but lacking the transmembrane domain; and (f) a nucleotide sequence complementary to any of the nucleotide sequences in (a), (b), (c), (d) or (e) above.
Further embodiments of the invention include isolated nucleic acid molecules that comprise a polynucleotide having a nucleotide sequence at least 90% identical, and more preferably at least 95%, 96%, 97%, 98% or 99% identical, to any of the nucleotide sequences in (a), (b), (c), (d), (e) or (f) above, or a polynucleotide which hybridizes under stringent hybridization conditions to a polynucleotide in (a), (b), (c), (d), (e) or (f) above. This polynucleotide which hybridizes does not hybridize under stringent hybridization conditions to a polynucleotide having a nucleotide sequence consisting of only A residues or of only T residues. An additional nucleic acid embodiment of the invention relates to an isolated nucleic acid molecule comprising a polynucleotide which encodes the amino acid sequence of an epitope-bearing portion of a Neutrokine-xcex1 polypeptide having an amino acid sequence in (a), (b), (c), (d) or (e) above. A further nucleic acid embodiment of the invention relates to an isolated nucleic acid molecule comprising a polynucleotide which encodes the amino acid sequence of a Neutrokine-xcex1 polypeptide having an amino acid sequence which contains at least one amino acid substitution, but not more than 50 amino acid substitutions, even more preferably, not more than 40 amino acid substitutions, still more preferably, not more than 30 amino acid substitutions, and still even more preferably, not more than 20 amino acid substitutions. Of course, in order of ever-increasing preference, it is highly preferable for a polynucleotide which encodes the amino acid sequence of a Neutrokine-xcex1 polypeptide to have an amino acid sequence which contains not more than 10, 9, 8, 7, 6, 5, 4, 3, 2 or 1 amino acid substitutions. Conservative substitutions are preferable.
The present invention also relates to recombinant vectors, which include the isolated nucleic acid molecules of the present invention, and to host cells containing the recombinant vectors, as well as to methods of making such vectors and host cells and for using them for production of Neutrokine-xcex1 polypeptides or peptides by recombinant techniques.
The invention further provides an isolated Neutrokine-xcex1 polypeptide comprising an amino acid sequence selected from the group consisting of: (a) the amino acid sequence of the full-length Neutrokine-xcex1 polypeptide having the complete amino acid sequence shown in FIGS. 1A and 1B (SEQ ID NO:2) or as encoded by the cDNA clone contained in ATCC No. 97768 deposited on Oct. 22, 1996; (b) the amino acid sequence of the predicted extracellular domain of the Neutrokine-xcex1 polypeptide having the amino acid sequence at positions 73 to 285 in FIGS. 1A and 1B (SEQ ID NO:2) or as encoded by the cDNA clone contained in ATCC No. 97768 deposited on Oct. 22, 1996; (c) the amino acid sequence of the Neutrokine-xcex1 intracellular domain (amino acid residues from about 1 to about 46 in FIGS. 1A and 1B (SEQ ID NO:2)) or as encoded by the cDNA clone contained in ATCC No. 97768 deposited on Oct. 22, 1996; (d) the amino acid sequence of the Neutrokine-xcex1 transmembrane domain (amino acid residues from about 47 to about 72 in FIGS. 1A and 1B (SEQ ID NO:2)) or as encoded by the cDNA clone contained in ATCC No. 97768 deposited on Oct. 22, 1996; and (e) the amino acid sequence of the soluble Neutrokine-xcex1 polypeptide having the extracellular and intracellular domains but lacking the transmembrane domain, wherein each of these domains is defined above.
The polypeptides of the present invention also include polypeptides having an amino acid sequence with at least 90% similarity, and more preferably at least 95% similarity to those described in (a), (b), (c), (d) or (e) above, as well as polypeptides having an amino acid sequence at least 80% identical, more preferably at least 90% identical, and still more preferably 95%, 96%, 97%, 98% or 99% identical to those above.
An additional embodiment of this aspect of the invention relates to a peptide or polypeptide which has the amino acid sequence of an epitope-bearing portion of a Neutrokine-xcex1 polypeptide having an amino acid sequence described in (a), (b), (c), (d) or (e) above. Peptides or polypeptides having the amino acid sequence of an epitope-bearing portion of a Neutrokine-xcex1 polypeptide of the invention include portions of such polypeptides with at least six or seven, preferably at least nine, and more preferably at least about 30 amino acids to about 50 amino acids, although epitope-bearing polypeptides of any length up to and including the entire amino acid sequence of a polypeptide of the invention described above also are included in the invention. In another embodiment, the invention provides an isolated antibody that binds specifically to an polypeptide having an amino acid sequence described in (a), (b), (c), (d) or (e) above.
The invention further provides methods for isolating antibodies that bind specifically to a Neutrokine-xcex1 polypeptide having an amino acid sequence as described herein. Such antibodies are useful diagnostically or therapeutically as described below.
The invention also provides for pharmaceutical compositions comprising soluble Neutrokine-xcex1 polypeptides, particularly human Neutrokine-xcex1 polypeptides, which may be employed, for instance, to treat tumor and tumor metastasis, infections by bacteria, viruses and other parasites, immunodeficiencies, inflammatory diseases, lymphadenopathy, autoimmune diseases, graft versus host disease and to stimulate peripheral tolerance, destroy some transformed cell lines, mediate cell activation and proliferation, and are functionally linked as primary mediators of immune regulation and inflammatory responses.
The invention further provides compositions comprising a Neutrokine-xcex1 polynucleotide or a Neutrokine-xcex1 polypeptide for administration to cells in vitro, to cells ex vivo and to cells in vivo, or to a multicellular organism. In certain particularly preferred embodiments of this aspect of the invention, the compositions comprise a Neutrokine-xcex1 polynucleotide for expression of a Neutrokine-xcex1 polypeptide in a host organism for treatment of disease. Particularly preferred in this regard is expression in a human patient for treatment of a dysfunction associated with aberrant endogenous activity of a Neutrokine-xcex1 gene.
The present invention also provides a screening method for identifying compounds capable of enhancing or inhibiting a cellular response induced by Neutrokine-xcex1 which involves contacting cells which express Neutrokine-xcex1 with the candidate compound, assaying a cellular response, and comparing the cellular response to a standard cellular response, the standard being assayed when contact is made in absence of the candidate compound; whereby, an increased cellular response over the standard indicates that the compound is an agonist and a decreased cellular response over the standard indicates that the compound is an antagonist.
In another aspect, a method for identifying Neutrokine-xcex1 receptors is provided, as well as a screening assay for agonists and antagonists using such receptors. This assay involves determining the effect a candidate compound has on Neutrokine-xcex1 binding to the Neutrokine-xcex1 receptor. In particular, the method involves contacting a Neutrokine-xcex1 receptor with a Neutrokine-xcex1 polypeptide and a candidate compound and determining whether Neutrokine-xcex1 polypeptide binding to the Neutrokine-xcex1 receptor is increased or decreased due to the presence of the candidate compound. The antagonists may be employed to prevent septic shock, inflammation, cerebral malaria, activation of the HIV virus, graft-host rejection, bone resorption, rheumatoid arthritis and cachexia (wasting or malnutrition)
The present inventors have discovered that Neutrokine-xcex1 is expressed not only in neutrophils, but also in kidney, lung, peripheral leukocyte, bone marrow, T cell lymphoma, B cell lymphoma, activated T cells, stomach cancer, smooth muscle, macrophages, and cord blood tissue. For a number of disorders of these tissues and cells, such as tumor and tumor metastasis, infection of bacteria, viruses and other parasites, immunodeficiencies, septic shock, inflammation, cerebral malaria, activation of the HIV virus, graft-host rejection, bone resorption, rheumatoid arthritis and cachexia (wasting or malnutrition, it is believed that significantly higher or lower levels of Neutrokine-xcex1 gene expression can be detected in certain tissues (e.g., bone marrow) or bodily fluids (e.g., serum, plasma, urine, synovial fluid or spinal fluid) taken from an individual having such a disorder, relative to a xe2x80x9cstandardxe2x80x9d Neutrokine-xcex1 gene expression level, i.e., the Neutrokine-xcex1 expression level in tissue or bodily fluids from an individual not having the disorder. Thus, the invention provides a diagnostic method useful during diagnosis of a disorder, which involves: (a) assaying Neutrokine-xcex1 gene expression level in cells or body fluid of an individual; (b) comparing the Neutrokine-xcex1 gene expression level with a standard Neutrokine-xcex1 gene expression level, whereby an increase or decrease in the assayed Neutrokine-xcex1 gene expression level compared to the standard expression level is indicative of a disorder.
An additional aspect of the invention is related to a method for treating an individual in need of an increased level of Neutrokine-xcex1 activity in the body comprising administering to such an individual a composition comprising a therapeutically effective amount of an isolated Neutrokine-xcex1 polypeptide of the invention or an agonist thereof.
A still further aspect of the invention is related to a method for treating an individual in need of a decreased level of Neutrokine-xcex1 activity in the body comprising, administering to such an individual a composition comprising a therapeutically effective amount of an Neutrokine-xcex1 antagonist. Preferred antagonists for use in the present invention are Neutrokine-xcex1-specific antibodies.